(29b) Simultaneous Electronic and Ionic Conduction In Block Copolymers

Balsara, N. P. - Presenter, University of California, Berkeley
Patel, S. N. - Presenter, University of California, Berkeley

Redox reactions occurring within battery electrodes require transport of both ions and electrons to the active centers. We report on the synthesis of a block copolymer, poly(3-hexyl thiophene)-b-poly (ethylene oxide) (P3HT-PEO), that exhibits simultaneous electronic and ionic conduction. Separate values of the electronic [(6.73±2.05) x 10-6 S/cm] and ionic [(1.09±0.469) x 10-4 S/cm] conductivity of a mixture of P3HT-PEO and a lithium salt were determined by a combination of AC impedance and DC techniques.  The P3HT-PEO/salt mixture was used to make lithium battery cathodes, with the active material LiFePO4 as the only other component.  All-solid lithium batteries were assembled to demonstrate that the P3HT-PEO/salt mixture serves all of the transport and binding functions required in the cathode.  The semiconducting nature of P3HT enables using cell potential to control charge transport within the electrode.